Chromone and flavonoid alkaloids are an important group of natural products possessing promising medicinal properties. Large number of naturally occurring chromone and flavonoid alkaloids are reported in the literature, varying in type of nitrogen system and its position of attachment on chromone/flavonoid nucleus. Their natural occurrence and biological activities have been recently reviewed by Khadem and Manes (Khadem, S. et. al. Molecules 2012, 17, 191). This class of alkaloids also led to discovery of potent anticancer molecule flavopiridol which received orphan drug status for treatment of Chronic myelogenous leukemia (reviewed in: Jain, S. K. et. al. Mini-Rev. Med. Chem. 2012, 12, 632). Rohitukine, 5,7-dihydroxy-2-methyl-8-[4-(3-hydroxy-1-methyl)-piperidinyl]-4H-1-benzopyran-4-one, is a chromone alkaloid originally isolated from leaves and stems bark of Amoora rohituka Roxb. (Meliaceae) (Harmon, A. D. et. al. Tetrahedron Lett. 1979, 8, 721) and then isolated as major component from the stem bark of Dysoxylum binectariferum Roxb. (Meliaceae) (Yang, D. H. et. al. J. Asian Nat. Prod. Res. 2004, 6, 233). Rohitukine was also isolated from barks of Schumanniophyton magnificum and S. problematicum (Rubiaceae) (Houghton, P. J. Planta Med. 1988, 54, 239; Houghton, P. J. et. al. Phytochem. Anal. 1993, 4, 9). Rohitukine showed moderate cytotoxicity against human HL-60 promyelocytic leukemia and HCT-116 colon cancer cells. Several more complex cytotoxic chromone alkaloids have been isolated from leaves and bark of Dysoxylum acutangulum of Meliaceae (Ismail, I. S. et. al. J. Nat. Prod. 2009, 72, 1879). Medicinal chemistry efforts around these nature-derived chromone alkaloid led to discovery of two promising clinical candidates for treatment of cancer viz. flavopiridol of Sanofi-aventis and P-276-00 of Piramal life sciences. (Naik, R. G. Tetrahedron 1988, 44, 2081; U.S. Pat. No. 4,900,727). With respect to bioactivities, many of these flavonoid and chromone alkaloids have been discovered through bioassay-guided chemical investigations, suggesting that they have significant potential for drug discovery.
Dysoxylum binectariferum is one of the plant in India of the Meliaceae family which mainly occurs in Western ghats of India. Rohitukine was found to be a major constituent of its bark extract, which is responsible for immunomodulatory activity (Mohanakumara, P. et al., Fitoterapia 2010, 81, 145-148; Naik, R. G. et al. Tetrahedron 1988, 44, 2081).